FIG. 1 is a side-sectional view illustrating part of a general linear compressor, and FIGS. 2 and 3 are a side-sectional view and a front view illustrating a conventional structure of discharging a refrigerant for the linear compressor, respectively.
Referring to FIG. 1, in the linear compressor, in a hermetic space of a shell (not shown), one end of a cylinder 2 is fixedly supported by a main body frame 3, and one end of a piston 4 is inserted into the cylinder 3, for forming a compression space P between the cylinder 3 and the piston 4. The piston 4 is connected to a linear motor 10 and reciprocated in the axial direction, for sucking a refrigerant into the compression space P and discharging the refrigerant.
Here, the compression space P for compressing the refrigerant is formed between one end of the cylinder 2 and the piston 4. A suction hole 4h is formed at one end of the piston 4 in the axial direction, for sucking the refrigerant into the compression space P, and a thin film type suction valve 6 is bolt-fastened to one end of the piston 4, for opening and closing the suction hole 4h. A discharge valve assembly 8 is installed at one end of the cylinder 2, for discharging the refrigerant compressed in the compression space P.
The linear motor 10 includes a ring-shaped inner stator 12 formed by laminating a plurality of laminations in the circumferential direction, and fixed to the outer circumference of the cylinder 2, a ring-shaped outer stator 14 formed by laminating a plurality of laminations in the circumferential direction outside a coil winding body formed by winding a coil in the circumferential direction, and disposed outside the inner stator 12 with an interval, and a permanent magnet 16 disposed in the space between the inner stator 12 and the outer stator 14, and linearly reciprocated by a mutual electromagnetic force by the inner stator 12 and the outer stator 14.
One end of the inner stator 12 is supported by the main body frame 3, and the other end thereof is fixed to the outer circumference of the cylinder 2 by a fixing ring (not shown). In addition, one end of the outer stator 14 is supported by the main body frame 3, and the other end thereof is supported by a motor cover 22. The motor cover 22 is bolt-fastened to the main body frame 3. The permanent magnet 16 is connected to the other end of the piston 4 by a connection member 30.
When a current is applied to the outer stator 14, the permanent magnet 16 is linearly reciprocated by the mutual electromagnetic force by the inner stator 12 and the outer stator 14, and the piston 4 is linearly reciprocated inside the cylinder 2. As a pressure inside the compression space P is varied, the suction valve 6 and the discharge valve assembly 8 are operated to suck, compress and discharge the refrigerant.
The conventional structure of discharging the refrigerant for the linear compressor will now be explained with reference to FIGS. 2 and 3. The conventional structure of discharging the refrigerant includes the discharge valve assembly 8 installed at one end of the cylinder 2 to be opened and closed, for discharging the refrigerant from the compression space P, a discharge cap 9 installed at one end of the cylinder 2 to cover the discharge valve assembly 8, for forming a discharge chamber D to which the refrigerant is discharged, and a loop pipe R connected to the discharge cap 9, for reducing noise and vibration of the high pressure discharged refrigerant. The discharge chamber D is partitioned off into discharge spaces 9a, 9b, 9c and 9d, for example, by a curved shape of the discharge cap 9.
In detail, the discharge valve assembly 8 includes a discharge valve 8a for opening and closing one end of the cylinder 2, a support cap 8b fixed to one end of the cylinder 2, for covering the discharge valve 8a, and a discharge valve spring 8c for elastically opening and closing the discharge valve 8a on one end of the cylinder 2 according to the pressure inside the compression space P.
Communication holes H1, H2, H3 and H4 for discharging the refrigerant to the discharge cap 9 are formed on the circumference of the support cap 8b at intervals. The discharge spaces 9a, 9b, 9c and 9d are formed on the discharge cap 9 to correspond to the communication holes H1, H2, H3 and H4, respectively. The discharge spaces 9a, 9b, 9c and 9d communicate to each other.
As the piston 4 is linearly reciprocated inside the cylinder 2, the refrigerant sucked into the compression space P is compressed. If the pressure inside the compression space P exceeds a set pressure, the discharge valve spring 8c is compressed to open the discharge valve 8a. The high pressure refrigerant of the compression space P is passed through the communication holes H1, H2, H3 and H4 of the support cap 8b, temporarily collected in the discharge chamber D inside the discharge cap 9, reduced in vibration and noise through the relatively thin and long loop pipe R, and externally discharged.
In the conventional structure of discharging the refrigerant for the linear compressor, the refrigerant compressed at a high pressure in the compression space P by linear reciprocation of the piston 4 generates a pulsation, passes through the communication holes H1, H2, H3 and H4 formed on the circumference of the support cap 8b of the discharge valve assembly 8 at intervals, and is discharged to the discharge chamber D which is one up-down and left-right symmetric limited space. That is, even if the pulsation is generated in the high pressure refrigerant, the refrigerant flows through the loop pipe P. Therefore, the pulsation of the refrigerant is maintained high, which increases noise and vibration.